As the massive 12-nation exercise involving 42 ships and 39 aircraft entered the fifth day, Malaysian civil aviation chief Azharuddin Abdul Rahman said its planes were now also searching in the southern part of the Andaman Sea.
Rahman confirmed that defence radar picked up an "indication" that the plane may have turned back from its intended flight path over the South China Sea. He said this was why the search operation had been extended to the Andaman Sea.
The US Federal Aviation Authority and the US National Transport Safety Board have been roped in to help track the missing aircraft.
The Beijing-bound Boeing 777-200 plane was carrying 227 passengers, including five Indians and one Indian-origin Canadian, and 12 crew members when it mysteriously vanished from radar screens an hour after taking off from Kuala Lumpur, triggering speculation that it may have been hijacked, crashed into sea or disintegrated mid-air.
"We will not spare any effort to find the missing plane. The search has been extended to two areas and we are now searching nearly 27,000 square nautical miles 12,425 square nautical miles in the Straits of Malacca and 14,440 square nautical miles in the South China Sea," Malaysia's Minister of Defence and acting Transport Minister Hishammuddin Hussein told reporters at a crowded press conference.
"Forty two ships and 39 aircraft have now been deployed in the search for MH370. Twelve countries have now joined the search, with India, Japan and Brunei being the latest to join the team," he said.
India on Tuesday offered help to Malaysia in search operations following which they sought assistance.
"We are ready to help. We are coordinating details with Malay side," the Spokesperson in the Ministry of External Affairs said in New Delhi.
The Indian Air Force said it has kept its aircraft on standby for taking part in the search operations.
The search area for the IAF is likely to be the Malacca Straits near the Andaman and Nicobar Islands.
The IAF has its Dornier aircraft along with the Mi-17 helicopters deployed in the Island territory and if the need be, the Navy can deploy the P-8I and the Tu-142 maritime surveillance aircraft.
India has a tri-services military command at Andaman and Nicobar islands and Navy and air force carry out regular patrols in the area.
As China and Vietnam criticised Malaysia for lack of information, Hussein denied "chaos" in search efforts and said they would never give up hope of finding the plane.
He said, "Unless we get the aircraft and the black box it is unlikely that we will be able to answer a lot of speculative issues that have been raised out there."
"The way forward is to bring more experts to analyse both the civilian and the military data, in the east or in the west, on land or in the water. This is exactly what we are doing. We are now working with many experts including from Boeing, the US Federal Aviation Authority and the US National Transport Safety Board," he said.
Meanwhile, Vietnam has said it is scaling back search operations in its waters.
"We've decided to temporarily suspend some search and rescue activities, pending information from Malaysia," deputy minister of transport Pham Quy Tieu said, adding that boats were still searching the area.